Current-regulating apparatus.



J. B. WANTZ. CURRENT REGULATIN'G APPARATUS.

APPLICATION FILED JULYZ4, 1916.

Patented Dec. 3, 1918.

l. B. WANTZ.

CURRENT REGULATING APPARATUS.

APPLICATION FILED lULY24. I9I6.

Ulluxnm Putt'inted Dec. 3, 1918.

2 SHEETS SHEET 2 m @J H w 7 2...... w 8 5 5 552 55% I. W321: Po P752502A UNITED STATES PATENT OFFICE.

JULIUS B. WANTZ, OF CHICAGO, ILLINOIS, ASSIGNOR T0 VICTOR ELECTRICCORPORA- TION, OF CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK.

CURRENT-REGULATING APPARATUS.

Specification of Letters Patent.

Patented Dec. 3, 1918.

Application filed July 24, 1 916. Serial No. 110,883.

To all whom it may concern Be it known that I, J ULIUS B. WAx'rz, acitizen of the United States, residing at Chicago, in the county of Cookand State of Illinois, have invented a new and useful Improvement inCurrent-Regulating Apparatus, of which the following is a specification.

My invention relates more particularly to current regulators for useunder conditions requiring relatively close regulation of the currentthroughout relatively wide variations in the current.

I have devised my improved regulator for use more especially inconnection with X-ray tubes of the so-called Coolidge type wherein theamount of X-ray producing high potential current which passes throughthe tube is dependent on the degree to which a filament forming aportion of the cathode is heated and provision is made for electricallyheating the cathode. In practice the desired range of intensity of theX-rays is obtained by varying the current for heating the cathodefilament between 2.75 to 5 amperes, a relatively wide range of intensityof X-rays being obtainable by a relatively slight change in the amountof heating current supplied to the tube. In view of this fact,relatively close regulation of the heat ing currentv supplied to thecathode through out the range of current-values, is required, ifrelatively close control of the tube current is desired. This closeregulation of heating current requires a correspondingly closeregulation of the primary current of the transformer whose secondarysupplies the heating current.

According to prior practice, it was customary to use either the commonform of resistance coil, or a choke coil. The common form of resistancecoil, however, presented the primary disadvantage of not permittingrelatively close regulation of the current between the current-values of4.5 and 5 amperes, while permitting close control at lower currentvalues; and the choke coil,

while permitting of the desired close adjustment for the high currentvalues, did not permit of sufficiently rapid actuation of the movablemember of the choke coil at the lower current values, to render itpracticable.

One of my primary objects is to provide a regulator whereby suiiicientlyclose regulation of the current throughout the range of values thereof,may be efiected without requiring undue movement of the movable elementof the regulator, during the adjustment for the lower current values.Another object is to provide an improved form of regulator which shallbe simple and eco nomical of construction and positive in operation.Another object is to calibrate the regulating apparatus in terms ofstrength of the heating current, or in other words, so calibrate it thatthe operator by looking at the apparatus and without making calculations, may determine the amount of heating current flowing through thecathode filament, this calibration being preferably in amperes, whichpresents the advantage of standardizing the technique furnished to theoperators.

Another object is to provide mechanism whereby the many varyingconditions which occur in the secondary of the transformer supplying theheating current, especially under its condition of use with an X-raytube of the Coolidge type, and energizing currents of varying voltage.within certain limits, may be'compensated for in order that the operatormay determine with sufficient accuracy, the amount of heating currenttraversing the cathode filament in any given position of the movableelement of the resistance device.

Referring to the accompanying drawings, Figure 1 is a plan view of myimproved apparatus, with a portion of the top plate broken away. Fig. 2is a section taken at the irregular line 2 on Fig. 1 and viewed in thedirection of the arrow. Fig. 3 is a view in elevation of a compensatingresistance for cooperation with the main re- "sistance device. Fig. 4 isa view in the nature of a diagram and partly perspective showing thecircuit connections of my improved resistance apparatus when used inconnection with an X-ray tube of the Coolidge type; and Fig. 5, a chartindicating the ideal relation. of the increase of heating currentthrough the cathode filament and the degree of movement of the handle ofthe resistance apparatus.

In the particular construction illustrated my improved apparatuscomprises a casing 10 formed of a base plate 11, a top plate 12 and acylindrical shell 13 forming the side wall of the casing, these partsbeing bolted together as by means of the bolts 14. The upper and lowerplates 12 and 11 contain alining openings 15 and 16, respectively, inwhi,h'a hollow shaft 17 is journaled. T he shaft 17 has rigidly securedthereto at its lower end a plate 18 having a depending boss 19 whichrests againstthe upper side of the plate 11 and positions the shaft 17against downward displacement. A similar plate 20 is rigidly secured tothe upper end of the shaft 17 below the top plate 12, these plates 18and 20 being thus spaced apart, as represented. In the constructionilli, trated the resistance elements of the apparatus are providedin'the form of coils 21 made of bare resistance wire wound spirally uponcylindrical members 22, preferably tubular, and formed of insulatingmaterial, such as porcelain, or of metallic tubingcovered withinsulating material. The tubes 22 are grouped about the axis ofthe-shaft 17 in an annular series and are rigidly held at theiroppositeends to the plates 18 and 20 in any desirable manner. In the arrangementshown each of the plates 18 and 20 contains a series of apertures 23,these apertures being equi-distantly spaced and arranged in an annularseries about shaft 17 these apertures in these two plates alining andthe portion of the wall of each being preferably formed of a springysection 24 partially cut from the plate carrying it and cooperating withthe screw 25. The ends of the tubes 22 project throughtheopenings 23 andare rigidly clamped in place by the screws 25. This method of clampingallows each unit to be moved individually in the direction of itsgreatest length so that the winding of resistance material on the unitis in a position in which they cooperate with the wiper 38.

The resistance coils 21, which are hereinafter more fully described, areelectrically connected in succession, the terminal of the last coil,represented at X in 4, being connected with a section of a switch devicerepresented at 26, secured to, and insulated from, the plate 18. Thisswitch device 26,

connected with a binding-post 31 of the resistance apparatus.

The switch-controlling member comprises a rod 32 slidable in alongitudinally extending bore 33 in the shaft 17 and carrying alaterally-projecting pin 34 which moves in a slot 35 in the shaft 17 andprojects into the space between the members 27 at which portion itcarries a sleeve 36 of insulating material, the device just describedoperating when the rod 32 is pulled upwardly to the position illustratedin Fig. 2, to separate .the switch members 27 and break the circuit.

In the particular arrangement illustrated, the coils 21 and the partssupporting them are adapted to be rotated about the axis of the shaft 17for controlling the amount of current passing through the coils, asthrough the medium of a hand-wheel 37 of insulating material, rigidlyconnected with the upper end of the shaft 17, the coils 21 cooperatingwith a relatively stationary contact member, or wiper, 38 whichis-preferably of the form illustrated and constructed ofcurrentconducting material. As shown, the contact 38 is provided with asleeve-portion 39 journaled on a shaft 40 rising from the plate 11. Thesleeve 39v rests upon a collar 41 secured to this shaft and connects atits upper end with one end of a torsion spring 42 which surrounds therod 40 and connects at its opposite end with a collar 43 secured to thisrod, the arrangement of the parts being such that the contact 38 extendsin an inclined position relative to the axis of each coil 21 and is ofsuch length and inclination that it will always be in contact with oneof the coils 21, regardless of the adjustment of these coils about theaxis of the shaft 17, it being preferred that these parts be so arrangedthat in the revolving of the coils 21 in either direction the contact 38will engage with the begining or end of one coil just before itdisengages the beginning or end of the preceding coil, as the case maybe, depending upon the direction in which the coils are revolved, sothat there will not be through the turning action produced by it on thesleeve 39, the contact member 38 is caused at all times to press againstthe coils in current value.

21 with the desired degree for insuring proper electrical contacttherebetween. The contact device 38 is electrically connected throughthe shaft 40, wire 71, wire 72 and compensating resistance 75 connectedwith these wires, to the other terminal 44 of the rheostat.

According to the preferred form in which I desire to provide my improvedregulating apparatus, provision is made for so proportioning themovement of the adjustable element of the regulator relative to thecontrol of the secondary current of the transformer associated with theregulator that with a load of given characteristics the variation in thesecondary current value will be constant for a given movement throughoutthe range of movement of this element of the regulator. In other words,the movement of the movable element of the regulator throughout a givennumber of degrees from any position relative to the stationary contactdevice will produce the same variation plished, according to thepreferred illustrated embodiment of my invention, with suflicientaccuracy for practical purposes, by so constructing the coils 21 thattheir resistances are such that the introduction into or removal of anyone coil into or from the circuit will always result in the sameincrease or decrease in heating current. In other words considering thenine coils 21 illustrated in the drawings, and which appear to be theproper number to be employed under all commercial conditions, thoughthey may be varied in number as desired, or other forms of resistanceprovided each coil is so wound and is so constructed that in themovement of any one of them entirely across the contact 38 the increaseor decrease in current passing from the secondary of the transformerthrough the cathode filament of the tube connected therewith, as thecase may be, is the same.

' In practice, any suitable method may be followed in determining theamount of resistance that each resistance coil 21 should present inorder that the result, or substantially the result, above referred tomay be accomplished. In view. however, of the many variables which existin the secondary circuit of the transformer, especially where it forms apart of an X-ray system in which a Coolidge X-ray tube is employed, Iprefer to determine the amount of resistance necessary to be furnishedby each coil, by the following method: Take, for example, the caseillustrated in the drawing wherein nine of the coils 21 are employed,the centers of these resistance units being equi-distant,

This result is accomt O 9 or40.

concerned the range of current passing from the secondary of a standardtransformer through the cathode filament of a standard Coolidge tube, asis the case in the particular example illustrated, is from 2.75 amperesto 5.25 amperes, or a difference of 2.5 amperes. Of this amount therange from 2.75 to 5.15 is only available in the device as preferablyconstructed, the other .10 amperes being unusable because of the stopdevice hereinafter referred to. If each resistance unit is to produceuniform variation in the heating current, each must decrease the currenta given amount, which in the case illustrated would be equal to .278amperes.

A resistance unit containing about twice as much resistance as it isthought necessary is first made by winding resistance wire on arelatively long tube, not shown, of small di- So far as the coils areconnected at one end to one of the primary terminals of a transformerfor the cathode filament of a Coolidge tube. The other primary terminalof this transformer and a contact which can be moved along the wire ofthe last-referred-to spiral for electrical contact therewith, areconnected with the terminals of an alternating current line having aslightly lower voltage than a standard line in which an ammeter isincluded to measure the current strength. The terminals of the secondaryof the said transformer are connected with the terminals of the cathodefilament of a Coolidge tube and an ammeter is placed in series with thisfilament. The operator then moves the mova-ble vcontact along theresistance spiral to cut resistance out of the primary circuit of thetransformer until the said ammeter in the secondary circuit registers2.75 amperes. The point at which this value of current flows is thenmarked on, or relative to, the resistance spiral and the reading of theammeter in series with the primary circuit of the said transformer, isnoted. The movable contact member is then moved farther along the saidresistance spiral until the The spiral thus formed would be ammeter inthe secondary circuit of the current will be very close to 5.25 amperes.With each operation of marking the points on the resistance spiral withwhich the movable contact registers for each increase of .278 amperes insecondary current, the operator carefully notes the value of the primarycurrent. The amount of resistance cut out by each of the said successivesteps is then measured and thus is determined the amount of resistanceeach of the respective coils 21 of the regulator, should have. With thisinformation before the one constructing the instrument, the windings foreach coil 21 are calculated so that each will have the requiredresistance and also have sufficient cross-sectional area to carry themaximum current without heating to an objectionable extent, as will bewell understood in practice. The amount of resistance wound on theseunits may be varied to cause the coils 21 to presentthe desired amountof resistance, either by using different sizes of wire or wire ofdifferent composition or changing the diameter of the spiral or varyingthe number of turns on the unit, or a combination thereof as desired.

By preference the apparatus is provided with a scale, illustrated at andcarried by the rotatable element of the apparatus, namely, that which isformed in part of the coils 21. This scale reads directly in amperes ofheating current and is uniformly graduated from 2.75 to 5.15. Theindicator 46 on the stationary part of the casing cooperates with thescale 45, the indicator, with a portion of the scale, being viewablethrough an opening 47 in the plate 12. The scale 45 is so mounted withreference to the relatively stationary contact 38 and to the indicator46 that under standard conditions, namely, with a gi en voltage acrossthe resistance coils 21 and the transformer in a circuit with a standardcathode filament of a Coolidge tube, the scale will indicate directly inamperas the value of the heating current.

To prevent the rotatable element of the apparatus from rotating in ananti-clockwise direction in Fig. 1 from a position in which theindicator registers with the marking 2.75 wherein all the resistance ofthe apparatus is in circuit, to a point in which all of the resistanceis cut out of circuit, I provide the stop-device hereinbefore referredto and represented at 48 which pro jects upwardly through an opening inthe plate 11 and coiiperates with a lug 49 depending from the plate 18.

Reference has been made to the compensating resistance 73. Thisresistance, which is very desirable under general commercial conditions,is provided for the purpose of compensating for variations in thevoltage of the service lines through which the transformers supplyingthe heating current to the Coolidge tubes, are energized, andcompensating for variations in the resistance of the cathode filament ofthe Coolidge tube. This compensating resistance, when employed, may takeany desired form, that shown comprising a resistance unit 50 formed ofbare resistance wire spirally wound upon a tube 51 covered withinsulating material, a plug 52 in the lower end of the tube, a threadedattaching device 53 extending through the plug and secured to, andinsulated from the plate 11 of the casing, the fastening device referredto extending downwardly through the tube 51 at a U-shape section 54thereof and a slidable contact device 55 on the member 53 exterior ofthe tube 50 and movable along, and in engagement with, the bare wireforming the coil 50. The wire 71 connects with the lower terminal of thecoil 50 and the wire 72 elec trically connects with the member 53 andconsequently is electrically connected with the contact 55.

In installing the described regulator-apparatus, as the currentcontroller for the cathode filamentof a Coolidge tube, the binding posts31 and 44 of the apparatus would be connected by wires 56 and 57 withone of the terminals of the alternating current generator 58, or anyother source of alternating current, and one of the terminals of theprimary 59 of a transformer, the other terminal of the primary of thistransformer being connected with the other terminal of the generator 58,or other power source. The'terminals of the secondary 60 of the saidtransformer are connected with the terminals of the cathode filament 61of a Coolidge tube represented at 62 and in series with which is anammeter 67. One of the terminals of this filament is wire 63 with thehigh potential rectifier 68 usually employed to supply the desired highpotential current for operating the tube 62, the rectifier 68 beingenergized by the secondary 64 of the high potential transformer throughthe medium of the wires 69 and 70. The primary 65 of this transformerwould be connected with the alternating current line, as is wellunderstood in the art, and the other terminal ofthe rectifier 68 isconnected by a wire 66 with the anode of the tube 62.

"With the apparatus set up as just described, the operator would set theregulator device so that the indicator 46 would register with any of theampere readings on the scale 45 and this reading would check with thereading of the ammeter 67. If these readings do not correspond, theoperator adjusts the contact 55 along the coil 50 until the readings docorrespond, and with this adjustment once made the readings on theconnected by a i scale 45 will correspond with the said am- I meterreadings sufiiciently closely for all practical purposes.

In Fig. 5 I have illustrated, by a diagrammaticchart, the relationbetween the variation of heating current and the movement of the movablepart of the regulator apparatus. From'this chart, which shows the idealcurve, it will be noted that for any given movement of the coils'thecurrent variation is a constant, the curve represented at Y beingsubstantially a straight line.

The greater the number of individual. coils the device is made up of thecloser will the curve for that device approach a straight line.Experience has shown that subdividing the device into a greater numberof coils than nine merely adds complications to the manufacturin processwithout any great gain of fidefity of control. The curve obtained from adevice having nine coils is sutliciently close to a straight line forthe work the device is to perform.

The switch-device 26, operated from the stem 32, presents a meanswhereby the circuit in which the resistance apparatus is located may beconveniently opened and closed at will, the grouping of thisswitch-operating member and the handle 37 particularly adapting theapparatus for X-ra work.

While I haveillustrated and escribed a particular construction in whichmy invention is embodied, I do not wish to be understood as intending tolimit it thereto, as the same may be variously modified and alteredwithout departing from the spirit of 'my invention.

What I claim as new, and desire to secure by Letters Patent, is:

1. In a current regulator, the combina tion of resistance units mountedto rotate, and a relatively stationary contact member supported toengage said units in succession as the latter are rotated and contacttherewith at difierent points in progression along their length.

2. In a current regulator, the combination of resistance units mountedto rotate ter at different points lengthwise of the same in succession.

tact member opposing the sides of said units and arranged to engage thelatter in succession at different points in progression along theirlength in the relative movement of said units and member.

6. In a current regulator, the combination of a plurality of rotatablysupported resistance units, and a relatively stationary contact membercooperating with said units and having a rotatably mounted section witha contact surface which extends at an angle to the axes of said units.

7. In a current regulator, the combination of a plurality of rotatablysupported resistance units, and a relatively stationary contact membercooperating with said units and having a rotatably mounted section witha contact surface which extends at an angle to the axes of said units,and means for holding said contact surface against the opposing surfacesof said resistance units.

8. In a current regulator, the combination of a plurality of rotatablysupported resistance units, and a relatively stationary contact member,cooperating with said units and having a rotatably mounted section witha contact surface which extends at an angle to the axes of said units,and spring means for holding said contact surface against the opposingsurfaces of said resistance units.

9. In a current regulator, the combination of a rotatably mounted shaft,and means on said shaft for mounting resistance units thereon, andadjustable to permit the said units to be adjusted in a directionparallel to the axis of said shaft.

10. In a current regulator, the combination of a rotatably mountedshaft. plates mounted on said shaft. resistance units, and means on saidplates for holding said units thereto constructed and arranged to permitof the adjustment of said units in a direction parallel to the axis ofsaid shaft.

11. In a current regulator, the combination of means for varying theamount of current passing through the regulator and including anoperating member, means for opening and closing the c1rcu1t through saidregulator, and a second operating member for controlling said last-namedmeans, mounted on said first-named operating member.

12. In a current regulator, the combination of means for varying theamount of current passing through the regulator and involving a tubularshaft providedwith a handle, and means for opening and closing thecircuit through said regulator including a shaft located in said tubularshaft and carrying a handle by which it may be operated.

13. In a current regulator, the combination of means for varying theamount of current passing through said regulator and including a tubularshaft provided with a handle, electric current-conducting members, ashaft located, and movable, in said tubular shaft, and means on saidsecondnamed shaft for controlling the position of said electriccurrent-conducting members relative to each other.

14. In a current regulator, the combination of means for varying theamount of current passing through said regulator and including a tubularshaft provided with a handle, a second shaft located, and movable, inthe opening in said first-named shaft, electric current-conductingmembers. and an insulated projection on said second-named shaftoperating when the latter is shifted, to control the position of saidelectric current-conducting members relative to each other. J

15. In a current regulator, the combination of a casing consisting of apair of plates spaced apart, a separating member between said plates,means clamping said plates against said separating member, and aplurality of resistance units and a contact member rotatable relative toeach other, said plates forming the bearings for the rotatable elementof the regulator.

16. In a current regulator, the combination of a casing consisting oftwo plates spaced apart; a separating member located between saidplates, bolts clamping said plates against said separating member, acontact member, and a plurality of resistance units arranged to engagesaid contact member, rotatably mounted in said casing.

17. In a current regulator, the combination of a plurality of resistanceelements and a contact-member rotatable relative to each other, a dialmounted on the rotating member and calibrated proportional to thestrengths of current obtainable through the circuit controlled by theregulator, and a stationary indicator cooperating with the graduationson said dial.

18. In a curren regulator, a contact member, an indicator, a graduatedscale cooperating with, and movable relative to, said indicator, and aplurality of resistance elements movable with said scale and cooperatingwith and movable relative to, said contact member.

19. In a current regulator, the combination of relatively movablemembers one of which comprises a plurality of resistance elements andthe other of which is a contact member for contacting with saidelements, and current-indicating means including cooperating members oneof which is a scale uniformly calibrated in amperes, one ofsaidlast-named members being movable with the movable one ofsaid'first-named members and the other of said last-named members beingrelatively stationary.

20. In current regulating means, a wound rotatable current-carryingmember and a cooperating stationary member and currentindicating meansincluding cooperating elements one of which is a graduated scale havingan indicating point which registers with the other of said elements whensaid current-regulating means passes a minimum value of current, a stopon said movable member and a cooperating relatively stationary stopserving to prevent the move-' ment of the rotating element of saidcurrent-indicating means in one direction beyo d said point of minimumcurrent.

21. In a current regulator. a wound rotatable current-carrying member, acotiperating stationary member. means whereby said first-named member isrotated with respect to said second-named member, a third member mountedon said fi st-named member to be rotatable with it. reference marks onsaid th rd m mber. a stationary indicator cooperating with saidreference marks. and means. for opening and closing the circuit throughsaid re ulator.

22. In a current regulator, a wound rotatable current-carrving member. acotincrating stationarv m mber. means wherebv said firstamed member isrotated with respect to said seco d-named member, a dial mounted on saidfirst-named member to be rota- 1W table with it. referencemarks on saiddial. a stationary indicator cotiperating with said reference marks. andmeans for opening and clo in the circuit throu h said regulator.

23. In a current regulator, a casing, a 11 wound rotatable member and astationary cooperating member inside said casing, -a third membermounted on said rotatable member so as to be rotatable with it,reference marks on said third member. an open- 12c ing in said casing. astationary indicator in said opening cooperating with said referencemarks. and switch mechanism to open the circuit through said regulator.

24. In a current regulator, the combination of a plurality of resistanceelements and a contact member rotatable relative to each other, a dialmounted on said rotatable member and calibrated in accordance with thestrength of the current passing through a we load ofgiven'characteristics in circuit with the regulator, and a stationaryindicator cooperating Withthe graduations on said dial.

25. In a current regulator, the combination of three or 'more resistanceelements arranged in a group and rotatable as a unit, a contact memberstationarily mounted relative to said resistance elements, and meansurging said contact member into contact In with said elements.

26. In a current regulator, the combination of three or more resistanceelements in the form of coils arranged in a group and mounted to rotateas a unit, a contact member stationary relative to said coils andadapted to engage the sides of the coils, and means urging said contactmember into contact with the coils in the rotation of the latter.

J. B. WANTZ.

